1. Field of the Invention
This invention relates to electric shavers, and more particularly to shavers having an oscillating cutting member, and having electric powered means for imparting longitudinal movements to the cutting member.
2. Description of the Related Art Including Information Disclosed Under 37 CFR .sctn..sctn.1.97-1.99
A number of different arrangements have been proposed and produced in the past, involving vibration-producing mechanisms for shavers of the type employing replaceable razor blades. U.S. Pat. No. 3,636,627 discloses one construction which employs a battery-driven electric motor mounted in the handle of a shaver and which has an eccentric weight on the end of the motor shaft to produce a gyrating effect to the entire unit, including the cutting blade or edge of the shaver.
Another construction is illustrated in U.S. Pat. No. 3,611,568. This involves a somewhat similar design, in that an eccentric weight is carried on the end of the shaft of an electric motor disposed in the handle of the shaver.
Still other devices are illustrated in U.S. Pat. Nos. 2,319,815 and 2,609,602. In patent '815 there is disclosed a razor blade and carrier therefor, both of which are movably mounted with respect to the handle of the shaver, and positively power driven by a motor-driven gyratory shaft having a governor weight and imparting reverse movements to the assembly, via a direct drive through the shaft. U.S. Pat. No. '602 relates to a construction wherein the blade is positively driven or reciprocated relative to the blade guard of the shaver.
U.S. Pat. No. 4,642,892 illustrates a number of shaver constructions involving reciprocation of a blade and its holder, by means of a direct drive. In the disclosed embodiments, an electric motor carries a bushing having an off-center shaft that cooperates with an apertured drive member, in order to effect a positive or driving reciprocation or oscillation of the blade.
While it is thought that some of the devices noted above operated in a satisfactory manner, it is believed that for the most part they generally suffered from a number of drawbacks. In cases where an eccentrically-mounted weight was employed, there was a tendency for the handle of the shaver to fully experience and dampen the vibration, as opposed to vibration of merely the blade. In addition, the use of eccentric weights gave rise to a gyrating type of movement, which is considered to have a deleterious effect on the shaving operation as well as on the skin of the user. Stated differently, with such constructions the blade was being forced edgewise into and withdrawn from the user's skin at a high rate of speed, typically at least one or two thousand times per second. There was thus a tendency for irritation to develop unless the magnitude of the vibrations was reduced to a very low value.
Where, in the prior art, reliance was had on relative movement between the blade and its holder, the tendency for lather and soap to penetrate the sliding surfaces and ultimately dry and harden, impaired the subsequent oscillatory movements of the blade.
Finally, most of the devices noted above were quite complicated, some involving multiple gear trains and drive shafts, and others having numerous components that were expensive to fabricate and difficult to assemble. Overall manufacturing cost thus made many of these devices unsuitable for the marketplace, and it is believed that the lack of acceptance of such devices is indicative of the drawbacks just mentioned.